Flow machines



Dec. 31, 1963 N. LAING 3,116,011

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Dec. 31, 1963 N. LAING FLOW MACHINES Filed Feb. 9, 1961 3 Sheets-Sheet 2 Iwvemoa g &

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' FLOW MACHINES Fil ed Feb. 9, 1961 3 Sheets-Sheet 5 I we To WW United States Patent Ofiice dlbfill Patented Dec. 31, 1963 3,116,011 FLOW MACHINES Nikolaus Laing, Rosenbergstrasse 2.4a, Stuttgart, Germany Filed Feb. 9, 1961, Ser. No. 88,088 Claims priority, application Germany Feb. 11, 1960 6 Claims. (Cl. 23045) This invention relates to flow machines for inducing movement of fluids which term is to be understood as comprehending both liquids and gases. The invention relates more particularly to flow machines of the kind (called hereinafter the kind described) comprising a cylindrical bladed rotor mounted for rotation about its axis and through which, in operation of the machine, fluid passes at least twice in a direction always transverse to the axis of the rotor.

The general object of the invention is to provide a flow machine of the kind described which can be adjusted as to output direction without altering the direction of rotation of the rotor: a specific object of certain embodiments of the invention is to provide a flow machine which is conveniently reversible as to general direction of flow, again without altering the direction of rotor rotation.

The invention accordingly provides a flow machine of the kind described wherein said guide means forms a structural unit which is movable as a whole to change the direction in which fluid is delivered by said machine Without altering the direction of rotation of the rotor. Preferably the guide means are rotatable about the rotor axis between two positions.

A particularly eflicient form of flow machine of the kind described is discussed in our copending application for Letters Patent, No. 20,871/57. Certain features mentioned in that application can with advantage be incorporated into a flow machine according to the invention. Thus preferably in such a machine the blades of the rotor are concave facing the direction of rotation and have their outer edges leading their inner edges, and said movable guide means provides a guide body extending the length of the rotor with constant cross-section and parallel thereto, the angles and curvature of the rotor blades being chosen so that (in operation) the rotor and the body form and stabilize an approximately cylindrical vortex including a field region with a velocity profile approximately that of a Rankine vortex and a core region eccentric to the rotor axis, the rotor having its interior clear of stationary guides at least over a major part of its crosssection adjacent the guide body.

Various embodiments of the invention will now be described by way of example with reference to the accom panying diagrammatic drawings in which:

FIGURES 1 and 2 are cross-sections showing one flow machine with movable guide means in two different positions;

FIGURES 3 and 4 are cross-sections of two further forms of flow machine;

FIGURES 5 and 6 are diagrams indicating how flow takes place in the machines of FIGURES 1 to 4;

FIGURE 7 is a cross-section of a further form of flow machine, and

FIGURE 8 is a perspective view of yet another flow machine.

Referring to the drawings, FIGURES 1 and 2 show a flow machine comprising a rectangular block designated generally B having end walls 1 and top and bottom members 2, 3 extending therebetween. The top member 2 presents a gently curved guide surface 4 towards the interior of the block; the bottom member presents two such surfaces 5, 6, which are concave and meet in a ridge 7 intermediate the sides of the block. A cylindrical rotor 10 is mounted for rotation between the end walls 1 of the block B, its axis ltla running lengthwise thereof. The rotor 10 has blades 11 which are concave facing the direction of rotation indicated by the arrow 12; the outer edges of the blades 11 lead their inner edges. Movable guide guide means are provided in the form of two members 13, 14 mounted between end plates 15 adjacent and parallel to the end walls 1 of the block B and mounted for rotation about the axis 14911 of the rotor 10. The members 13, 1d and their supporting plates 15 form a single structural guide unit movable as a whole between the two positions shown in FIGURES 1 and 2, and designated generally G.

Each of the members 13, 14 presents a guide wall 16, 17 to the rotor 10 which is divided into two parts, an entry part 16a, 17a and an exit part 16b, 17b, the entry wall parts converging towards and guiding flow into the rotor and the exit wall parts diverging from and guiding flow away from it. The exit wall part 17b, which is the part of the guide means chiefly influencing flow through the rotor 10, presents a concave surface to the rotor which converges therewith in the direction of rotor rotation. The wall part 17b extends over only some 20 of the rotor circumference. The exit wall part 16b diverges from the rotor 1d from a point 18 where it is separated by one third (or slightly more) of the radial depth of the rotor blades 11 from the outer envelope, the entry and exit arcs of the rotor 1t) dividing at this point 18. The exit wall part 16b has a radius from the rotor axis 10a which increases monotonically in the direction of rotor rotation.

In operation of the machine, whether in the FIGURE 1 or the FIGURE 2 position, a vortex approximating to a Rankine vortex is set up the core of which is eccentric to the rotor axis and indicated by the flow lines shown chain-dotted at V: the whole throughput flows twice through the rotor blades 11 from the suction zone S to the pressure zone P in a direction always perpendicular to the rotor axis 119a as indicated in general direction only by the chain dotted flow lines F.

#FIGURE 5 shows an ideal relation of the vortex to the rotor 1, and the distribution of velocity in the vortex. The line 41 represents a small part of the inner envelope of the rotor blades 11, projected on to a straight line, while the chain dotted line 41 represents a radius of the rotor taken through the axis 42 of the vortex core V. Velocity of fluid at points on the line 41 by reason of the vortex is indicated by the horizontal lines 43a, 43b etc., the length of each line 43a, 4312 etc. being a measure of the velocity at the point 43a, 43b etc. respectively. The envelope of these lines is shown by the curve 44, which has two portions, one 44a approximately a rectangular hyperbola and the other, 44b a straight line. The curve 44a relates to the field region of the vortex and the curve 44b to the core: it will be understood that the curves are those of an ideal or mathematical Rankine vortex and actual flow conditions will only approximate to these curves.

The core V of the vortex is a whirling mass of air with no translational movement as a whole, and velocity diminishes going from the periphery of the core to its axis 42. The core V intersects the inner blade envelope indicated at 41} and an isotach I osculates the envelope, in the manner of a gear wheel meshing with an internal gear ring. The vortex core V is a region of low pressure, and the location of the core can be discovered by investigation of pressure distribution within the rotor. Although for convenience the vortex core V has been shown circular and has been regarded as possessing an axis, the core will usually not be truly circular.

The velocity profile of the fluid at the second entrance thereof to the rotor blades 11 will be that of the vortex.

In the ideal case of FIGURE 5 this profile will be that of the Rankine vortex there shown by curves 44a, 44b; in an actual case the profile will have the general character of a Rankine vortex. Thus there will be in the region of the periphery of the core V a flow tube of high velocity indicated at ME in FIGURES l and 2 by the heavier chain dots while the flow tubes remote from the periphery of the core will have a very much smaller velocity. It will be appreciated that much the greater amount of air flow in the flow tubes in the region of maximum velocity.

FIGURE 6 illustrates in an idealized manner a number of flow tubes F under the influence of a Rankine vortex. The core region is shown shaded, and the maximum velocity flow tube MF undergoes a change of direction of about 180 in passing through the interior of the rotor. Including the traversal-s of the blades the change of direction will then exceed 180. It is particularly to be noted that the major part of the throughput (represented by the flow tube MF) passes through the rotor blades where they have a component of velocity in a direction opposite to the main direction of flow within the rotor indicated in FIGURE 6 by the arrow A.

It is considered that the blade angles and blade curvature determine the character of the vortex While the position of the vortex core is determined by means of the guide body provided in the example of FIGURE 1 by the wall part 17b. It is considered that in a given case the particular blade angles and blade curvature depend on the following parameters among others: the diameter of the blades, the depth of a blade in radial direction, the density and viscosity of the fluid, the dispositions of the external guide body, the rotational speed of the rotor, as well as on the ratio between overall pressure and back pressure. adapted to correspond to the operating conditions ruling in a given case; to obtain the best results by means of a vortex as just described requires in any given case the adoption of quite definite blade angles and curvature. (Blade curvature is in this connection to be understood to means not only the curvature of a blade of uniform thickness, but also the curvatures of the contours of profiled blades.) Whether or not the angles and curvatures have been fixed at optimum values is to be judged by the criterion that the flow tubes close to the vortex core should be deflected by approximately 180. The creation of a vortex such as discussed above leads to a greatly increased efficiency at low Reynolds numbers; for an explanation of this the specification of our previously mentioned copending application No. 20,871/57 is referred to.

Of course in a particular construction other considerations may cause a designer to deviate from what is considered purely from the point of view of flow is the optimum. Indeed the flow lines in a particular case will probably not correspond entirely as to the position of the vortex core V with the idealized views of FlGURES 5 and 6. Thus the latter figures show that it is desirable to have the axis of the core V within the inner blade envelope 6 so that the isotach I within the core osculates that envelope; however, this is not essential and is not the case in the FIGURE 1 construction.

It will nevertheless be seen that despite divergences of the flow conditions of FIGURES 1 and 2 from the ideal, the maximum velocity flow tube MF with which is associated the major part of the throughput is turned through an angle well over 90 in passing from suction to pressure region and that it passes through the rotor blades where these have a velocity with a component opposite to the main direction of flow through the rotor, indicated by the arrow A.

In either the FIGURE 1 or the FIGURE 2 position of the guide unit G the guide surfaces 4, 5, 6 are too far from the rotor Iii to have any appreciable effect on flow of fluid through it. The guide surfaces 5, 6 do These parameters must be 4 however define two alternative outlet directions one to the left hand side of the block B as seen in FIGURES 1 and 2 and the other to the right hand side thereof. In the FIGURE 1 position of the guide unit G fluid leaving the rotor It) is deflected by the surface 5 more or less horizontally to the left: to assist this deflection a baffie 20 is mounted between the end walls 1. The free edge 160 of the wall part 1612 and the free edge 50 of the guide surface 5, and the two end walls 1, define the outlet of the machine in the FIGURE 1 position of the guide unit G. When the guide unit is moved to its FIGURE 2 position, fiuid leaving the rotor is deflected by the surface 6 to the right and somewhat downwardly. In this position the wall part 1617 fairs into the surface 6, and the edges 17c and 6c of the wall part 1712 and of the surface 6 respectively define, with the end walls 1, the outlet of the machine. In the FIGURE 1 position of the guide unit G the fluid inlet is defined by the right hand edge 4a of the guide surface 4, the free edge 17d of the wall part 17a and the end walls 1. In the FIG- URE 2 position of the unit G the inlet is defined by the left hand edge 4b of the surface 4, the edge 16d of the wall part 16a and the end walls 1. Thus in the FIG- URE 1 position of the guide unit G fluid is received from the right hand side of the block B and discharged to the left. In the FIGURE 2 position of the guide unit G fluid is received from the left hand side and discharged to the right. Thus simply to rotate the guide unit G by some 30 reverses the flow across the block B.

The FIGURE 1 construction accordingly lends itself to use as a reversible blower for insertion in walls or windows to bring fresh air into a room or discharge spent air therefrom at will. This task has normally been performed in the past by axial fans driven by reversible motors: the present invention, in this embodiment, provides not only a particularly efficient blower but a means of reversing flow without using a reversible motor.

The construction and operation of the flow machines of FIGURES 3 and 4 will be readily understood from the foregoing: similar parts are given the same reference numerals and no further description will be necessary. In each figure the guide walls 16, 17 are secured together to form a single structural unit G which is rotatable about the rotor axis between the position shown in full lines and the position shown dotted: in FIGURE 3 this movement is about in FIGURE 4 some In both figures fixed guide means are provided defining openings 25, 26: in the full line position of the guide unit G opening 25 provides the inlet for the machine and opening 26 the outlet, while in the dotted position of the guide unit G opening 26 is the inlet and opening 25 the outlet. To avoid confusion flow through the machine has been indicated in each case only for the full line position of the guide unit G. It will however readily be seen how flow takes place in the dotted position of the guide unit, from the foregoing discussion with reference to FIGURES 1, 2, 5 and 6. In both positions of the guide unit G in both figures, a vortex forms in operation adjacent the guide wall part 17b and interpenetrating the rotor blades.

The FIGURE 7 flow machine comprises a rotor similar to that of FIGURES 1 and 2 and indicated by the same numeral It). The rotor is mounted between plane vertical end plates 71 and shaped top and bottom plates 72, 73 secured thereto which define offset ducts 74, 75; when flow takes place in the manner indicated these ducts 74, 75 provide respectively inlet and outlet ducts. A guide body 76 extends the length of the rotor 10 within the interior thereof and is mounted for angular movement about the rotor axis by about between full-line and dotted positions as shown in the figure. The guide body 76 is of aerofoil cross-section with its median line curved without point of inflection.

With the guide body 76 in its position shown in full lines, flow takes place as indicated by the arrows. With the guide body 76 in its dotted position flow takes place in the reverse direction. The fixed guide means provided by the plates 72, 73 have no appreciable influence on flow through the rotor.

The guide body 76 can be replaced by two or more guide bodies arranged in parallel relation and movable as a unit. A variety of suitable forms of guide body are described in British patent application No. 44,292/60.

FIGURE 8 shows a flow machine according to a modification of the invention. The machine incorporates two rotors 10a, 10b each like the rotor 10 of FIGURES 1 and 2, the rotor 10a being operative on rotation in the direction of the arrow 12a and the rotor 1% being operative on rotation in the direction of the arrow 12b. The rotors are secured together on the same shaft 80: their ends are closed, as is the case with all the rotors herein described, and they are separated by an intermediate disc. Ducts designated generally Da, Db respectively are associated one with each rotor. This ducting includes plane end walls 81a, 81a; 81b, 81b running perpendicular to the axis and curved upper and lower walls 8. Each duct and its associated rotor forms a flow machine operating on the general principles enunciated with reference to FIGURES and 6, when the rotor turns in the appropriate direction. When the rotor turns in the opposite direction no flow takes place through it. Thus, considering the machine as a whole rotation of the shaft 80 in one direction produces a flow in one direction, while reversal of the direction of rotation reverses the direction of flow.

I claim:

1. A flow machine comprising a first structural unit providing opposed first and second flow guide surfaces extending between opposite sides of the unit, said sides being open, a second structural unit also providing opposed first and second flow guide surfaces, said second unit being supported on the first unit between the flow guide surfaces thereof for angular movement about an axis between two predetermined positions, all said guide surfaces having their generators substantially parallel to the axis, and a rotor mounted between the flow guide surfaces of the second unit for rotation about said axis in one direction only, the rotor having curved blades the outer edges of which lead in said direction of rotation, said first flow guide surface of the second unit including a vortex-stabilizing portion and said second flow guide surface of the second unit including a portion diverging from the rotor opposite said vortex-stabilizing surface portion, both said flow guide surfaces being spaced from the rotor by more than a working clearance, said first and second flow guide surfaces of said second unit cooperating respectively with said first and second flow guide surfaces of said first unit in one said predetermined position of the second unit for flow in one direction between said opposite sides of the first unit, said first and second flow guide surfaces of said second unit cooperating respectively with said second and first flow guide surfaces of said first unit in the other said predetermined position of the second unit for flow in the order direction between opposite sides of the first unit.

2. A flow machine as claimed in claim 1, wherein said predetermined positions of the second unit are separated by less than 90 and one guide surface of the first unit comprises two portions, one to deflect impinging flow to one said side and the other to deflect impinging flow to the other said side.

3. A flow machine comprising a first structural unit providing opposed first and second flow guide surfaces extending between opposite sides of the unit, said sides being open, a second structural unit also providing opposed first and second flow guide surfaces, said second unit being supported on the first unit between the flow guide surfaces thereof for angular movement about an axis between the two predetermined positions, all said guide surfaces having their generators substantially parallel to the axis, and a rotor mounted between the flow guide surfaces of the second unit for rotation about said axis in one direction only, the rotor having curved blades the outer edges of which lead in said direction of rotation, said first flow guide surface of the second unit including a vortex-stabilizing portion and said second flow guide surface of the second unit including a portion diverging from the rotor opposite said vortex-stabilizing surface portion, both said flow guide surfaces being spaced from the rotor by more than a working clearance, said second flow guide surfaces of the first and second units cooperating in one said predetermined position of the second unit to block off fluid flow to the rotor from one side of the first unit, said sec ond flow guide surface of the first unit cooperating with the first flow guide surface of the second unit in the other said predetermined position to block off fluid flow to the rotor from the other side of the first unit, flow in each said predetermined position taking place towards the side from which flow is blocked.

4. A flow machine as claimed in claim 3, wherein in each said predetermined position the vortex-stabilizing surface portion is located for flow from the rotor towards the first flow guide surface of the first unit, said last mentioned surface having a portion which diverts flow to said one side in the first predetermined position of the second unit and another portion which diverts flow to said other side when the second unit is in said other predetermined position, said predetermined positions being separated by no more than 5. A flow machine comprising a first stationary unitary structure defining a pair of openings and flow guide surfaces associated therewith, a second unitary structure also providing flow guide surfaces and mounted within said first structure for angular movement between two predetermined positions, about an axis which is fixed with respect to the first structure, a rotor mounted within said second unitary structure for rotation about said axis in one direction only, the rotor having curved blades the outer edges of which lead in said direction of rotation, said rotor and said guide surfaces of the second structure cooperating to guide fluid through the rotor in a curved path defined by the position of the second structure, the guide surfaces of the first and second structures cooperating in one said position of the latter for flow in one direction between said openings, the guide surfaces of the first and second structures cooperating in the other position of the latter for flow in the other direction between said openings.

6. A flow machine comprising a first structural unit defining two openings and providing flow guide surfaces, a second structural unit supported in the first unit for angular movement about an axis between two predetermined operating positions, said second unit providing first and second opposed guide surfaces, said guide surfaces all having their generators substantially parallel to the axis, and a rotor mounted between the flow guide surfaces of the second unit for rotation about said axis in one direction only, the rotor having curved blades the outer edges of which lead in said direction of rotation, said first flow guide surface of the second unit including a vortex-stabilizing portion and said second flow guide surface including a portion diverging from the rotor opposite said vortexstabilizing portion both said surfaces being spaced from the rotor by more than a working clearance and defining an entry are to the rotor and an exit arc therefrom, said second unit in one said predetermined position exposing the entry are of the rotor to one opening and the exit arc to the other, and said second unit in the other said predetermined position exposing the entry arc of the rotor to the other opening and the exit arc to said one opening, at least one guide surface of the second unit being aligned in each predetermined position with one margin of that opening which is opposite the exit arc of the rotor.

(References on following page) References Cited in the fi1e of this patent 340,947 UNITED STATES PATENTS 581,

2,212,113 Couch Aug. 20, 1940 559,024 2,335,437 Morgan et a1. Nov. 30; 1943 5 596,328 2,711,283 Troxell June 21, 1955 7 14 2,914,243 Eek Nov. 24, 1959 1,074,816

FOREIGN PATENTS 337,300 Switzerland May 15, 1959 10 8 Switzerland Oct. 31, 1959 Italy Aug. 23, 1958 Belgium Jan. 6, 1958 Great Britain Jan. '1, 1948 Great Britain Sept. 6, 1961 Germany Feb. 4, 1960 

1. A FLOW MACHINE COMPRISING A FIRST STRUCTURAL UNIT PROVIDING OPPOSED FIRST AND SECOND FLOW GUIDE SURFACES EXTENDING BETWEEN OPPOSITE SIDES OF THE UNIT, SAID SIDES BEING OPEN, A SECOND STRUCTURAL UNIT ALSO PROVIDING OPPOSED FIRST AND SECOND FLOW GUIDE SURFACES, SAID SECOND UNIT BEING SUPPORTED ON THE FIRST UNIT BETWEEN THE FLOW GUIDE SURFACES THEREOF FOR ANGULAR MOVEMENT ABOUT AN AXIS BETWEEN TWO PREDETERMINED POSITIONS, ALL SAID GUIDE SURFACES HAVING THEIR GENERATORS SUBSTANTIALLY PARALLEL TO THE AXIS, AND A ROTOR MOUNTED BETWEEN THE FLOW GUIDE SURFACES OF THE SECOND UNIT FOR ROTATION ABOUT SAID AXIS IN ONE DIRECTION ONLY, THE ROTOR HAVING CURVED BLADES THE OUTER EDGES OF WHICH LEAD IN SAID DIRECTION OF ROTATION, SAID FIRST FLOW GUIDE SURFACE OF THE SECOND UNIT INCLUDING A VORTEX-STABILIZING PORTION AND SAID SECOND FLOW GUIDE SURFACE OF THE SECOND UNIT INCLUDING A PORTION DIVERGING FROM THE ROTOR OPPOSITE SAID VORTEX-STABILIZING SURFACE PORTION, BOTH SAID FLOW GUIDE SURFACES BEING SPACED FROM THE ROTOR BY MORE THAN A WORKING CLEARANCE, SAID FIRST AND SECOND FLOW GUIDE SURFACES OF SAID SECOND UNIT COOPERATING RESPECTIVELY WITH SAID FIRST AND SECOND FLOW GUIDE SURFACES OF SAID FIRST UNIT IN ONE SAID PREDETERMINED POSITION OF THE SECOND UNIT FOR FLOW IN ONE DIRECTION BETWEEN SAID OPPOSITE SIDES OF THE FIRST UNIT, SAID FIRST AND SECOND FLOW GUIDE SURFACES OF SAID SECOND UNIT COOPERATING RESPECTIVELY WITH SAID SECOND AND FIRST FLOW GUIDE SURFACES OF SAID FIRST UNIT IN THE OTHER SAID PREDETERMINED POSITION OF THE SECOND UNIT FOR FLOW IN THE ORDER DIRECTION BETWEEN OPPOSITE SIDES OF THE FIRST UNIT. 